A passive optical network (PON) is one of the technologies used to distribute internet data to customer premises. In a PON Network, all signals in the upstream direction (i.e. from clients to a Central Office (CO)) are passively combined before being received by the CO. A modem at the client side is called ONU (Optical Network Unit), while the device in the CO, which receives the combined data from multiple ONUs, is called OLT (Optical Line Termination). For the structure to work, only one ONU sends data at a given time, and all ONUs have to operate at the same exact frequency. The OLT receives one burst of data per ONU, and is in charge of synchronizing ONUs, via the downstream direction.
However, the channels between each ONU and the shared OLT can be different (e.g. different ONU types and different fiber lengths), and one of the weak aspects is the measurement of the upstream link quality. The parameters that are used in conventional devices when measuring the upstream link quality are the received optical power and the bit error rate (BER), which do not provide accurate upstream link quality measurements. Further, conventional techniques that rely upon optical power and the bit error rates will not provide information related to links not showing bit errors. That is, conventional techniques relying upon optical power and bit error rates may not detect link quality degradation over time, where channel degradation will not be detected before a link is actually showing bit errors.
Accordingly, there is a need for an efficient circuit for and a method of implementing a bursty phase detector in a receiver.